Only 70 of the 665 drivers asked to sit a licence test after authorities uncovered a scam involving fraudulent driving certificates have obtained a proper licence.

Forty-nine of the drivers, who were issued with fake certificates of competence by a former Linfox driver who allegedly misused his VicRoads accreditation to endorse commercial vehicle licences in the state, failed the retest.

Some 126 drivers had surrendered their heavy vehicle licences, with 284 failing to make an appointment and undergo the new test.

Another five did not turn up for the retest, VicRoads Chief Executive Gary Liddle says.

Victoria Police is investigating the actions of an accredited training provider at the Linfox-operated Anglesea Complex, which is permitted to carry out driver testing.